Great efforts in studies and researches are currently being made to be able to apply a diamond to usages as semiconductor device materials. Semiconductor devices employing diamonds can stably operate even in harsh environments of a high temperature, a space or the like, and can also cope with high-speed high-output operations, resulting in increasing demand.
The applicability of diamonds as semiconductor device materials requires a conductivity type control pertaining to p-type or n-type. P-type semiconductor diamond can be easily obtained for example by introducing a boron-containing chemical compound as impurity source into a chamber during chemical vapor deposition (CVD).
On the other hand, n-type semiconductor diamond, whose synthesis has hitherto been deemed difficult can now be obtained by causing diamond to grow epitaxially on while n-doping with phosphorus the single-crystalline {111} diamond substrate. Further, there has been proposed a diamond UV light emitting element having a pn junction structure, in which a phosphorus-doped n-type semiconductor diamond thin film is laminated on the surface of a boron-doped p-type semiconductor diamond thin film formed on the electrically conductive single crystal {111} diamond substrate (non-patent document 1).
[Non-patent Document 1]
“NEW DIAMOND,” Japan New Diamond Forum, 2001, Vol. 17, No. 4, p. 10–16.